Director Clark Gregg, who adapted Chuck Palahniuk's novel for the big screen, opted to film scenes in an abandoned New Jersey psychiatric hospital, where one crew member saw a ghost.
Gregg recalls, "This hospital was a collection of maybe 70 buildings, built in 1910; it was a city for the insane called Overbrook. It's now down to five buildings and they were all abandoned.
"We had these very tough guy cops who were there training police dogs while we were shooting and they were so matter of fact that there were two ghosts in two different buildings. One was kind of a sexy turn-of-the-century Florence Nightingale nurse ghost, but the other wasn't so friendly.
"Building five had this unspeakable satanic dark energy. The crew member who walked into that building and had this experience with a ghost was not even capable of speaking about it - still isn't."